Posted by Cris (24.66.94.141) on November 08, 2003 at 11:23:29:
In Reply to: Locking back and locking forward posted by Juerg on November 08, 2003 at 10:12:47:
Great topics. I include the first few paragraphs of a fatigue paper for those who may have missed it in earlier posts. It fits with this post.
Outside of obvious injury, any drop in performance during exercise or competition, is due to fatigue. The specific mechanism of fatigue or multiple mechanisms of fatigue may or may not be immediately obvious, and at times not well understood or explainable with our current knowledge. Fatigue may be defined as; a condition of cells, tissues, or organs, which, as a result of excessive activity, temporarily lose the power to respond to further stimulation- Webster’s. In the field we may define fatigue as any decrease in the ability to produce power or sustain proper technique.
Specific mechanisms of fatigue can be described in general terms that pertain to how the athlete feels: out of breath, losing strength, and losing mental focus. We might include “burning sensation”, as a warning that fatigue, although not yet present, is imminent if pace is maintained. We may also describe fatigue in more scientific terms. Currently there is no standardized consensus on specific categories of fatigue. The following categories are some of the more popular references to specific types of fatigue.
Types of Fatigue:
Neuromuscular Fatigue
Metabolic Fatigue
Structural Fatigue
Neuroendocrine Fatigue
Psychological Fatigue
Although we may be able to define scenarios where one of these systems is taxed causing fatigue, it is more likely that more than one system can be taxed to fatigue simultaneously during exercise, and that fatigue in one system may contribute to reduced function in another. Because of this it is important to view these categories as somewhat loose divisions of possibly interrelated-interdependent systems. For example an athletes muscles may stop working because they “hit the wall”, (depleted glycogen), or reached acidosis (measured by blood lactate accumulation). Both, in fact may be measurable at the same time. A runner may be pushing hard near the end of a long race. The increased intensity may push them deep into anaerobic glycolysis, saturating the muscle with lactic acid, or more precisely a reduction in muscle pH with increased muscle H+ disassociated from lactate. At the same time the athlete has all but depleted glycogen stores from exhaustive aerobic glycolysis. For the athlete it would feel like their legs are heavy, weak, possibly cramping, and losing speed, but inspired by the finish line being minutes away, they decide to pick up the pace and give everything they have. As they approach the finish line the burn is almost unbearable, and a feeling of muscles seizing is present. More than one source of fatigue has influenced this athlete’s performance.